XenAPI: Support local connections

Currently there is no way to connect to XAPI through the unix socket,
requiring a URL and credentials.

This change allows you to run in dom0 (particularly in xenserver-core
environments) and connect to XAPI using the unix domain socket by
specifying "unix://local"
DocImpact

Change-Id: I3d5ace31c9c0411fa711cfdf87383d36f61bfa4a

etc/nova/nova.conf.sample

@@ -2194,8 +2194,10 @@
 # Options defined in nova.virt.xenapi.driver
 #
 
-# URL for connection to XenServer/Xen Cloud Platform. Required
+# URL for connection to XenServer/Xen Cloud Platform. A
-# if compute_driver=xenapi.XenAPIDriver (string value)
+# special value of unix://local can be used to connect to the
+# local unix socket.  Required if
+# compute_driver=xenapi.XenAPIDriver (string value)
 #xenapi_connection_url=<None>
 
 # Username for connection to XenServer/Xen Cloud Platform.

nova/tests/virt/xenapi/stubs.py

@@ -62,7 +62,7 @@ def stubout_session(stubs, cls, product_version=(5, 6, 2),
 
 
 def stubout_get_this_vm_uuid(stubs):
-    def f():
+    def f(session):
         vms = [rec['uuid'] for ref, rec
                in fake.get_all_records('VM').iteritems()
                if rec['is_control_domain']]

nova/tests/virt/xenapi/test_vm_utils.py

@@ -187,7 +187,7 @@ class XenAPIGetUUID(test.TestCase):
 
         self.mox.ReplayAll()
         self.assertEquals('2f46f0f5-f14c-ef1b-1fac-9eeca0888a3f',
-                          vm_utils.get_this_vm_uuid())
+                          vm_utils.get_this_vm_uuid(None))
         self.mox.VerifyAll()
 
     def test_get_this_vm_uuid_old_kernel_reboot(self):
@@ -204,7 +204,7 @@ class XenAPIGetUUID(test.TestCase):
 
         self.mox.ReplayAll()
         self.assertEquals('2f46f0f5-f14c-ef1b-1fac-9eeca0888a3f',
-                          vm_utils.get_this_vm_uuid())
+                          vm_utils.get_this_vm_uuid(None))
         self.mox.VerifyAll()
 
 
@@ -891,6 +891,7 @@ class GenerateDiskTestCase(stubs.XenAPITestBase):
         stubs.stubout_session(self.stubs, fake.SessionBase)
         driver = xenapi_conn.XenAPIDriver(False)
         self.session = driver._session
+        self.session.is_local_connection = False
         self.vm_ref = fake.create_vm("foo", "Running")
 
     def tearDown(self):

nova/tests/virt/xenapi/test_xenapi.py

@@ -325,6 +325,7 @@ class XenAPIVMTestCase(stubs.XenAPITestBase):
         self.project_id = 'fake'
         self.context = context.RequestContext(self.user_id, self.project_id)
         self.conn = xenapi_conn.XenAPIDriver(fake.FakeVirtAPI(), False)
+        self.conn._session.is_local_connection = False
 
         fake_image.stub_out_image_service(self.stubs)
         set_image_fixtures()
@@ -3653,14 +3654,33 @@ class XenAPIInjectMetadataTestCase(stubs.XenAPITestBase):
 
 class XenAPISessionTestCase(test.TestCase):
     def _get_mock_xapisession(self, software_version):
-        class XcpXapiSession(xenapi_conn.XenAPISession):
+        class MockXapiSession(xenapi_conn.XenAPISession):
             def __init__(_ignore):
                 "Skip the superclass's dirty init"
 
             def _get_software_version(_ignore):
                 return software_version
 
-        return XcpXapiSession()
+        return MockXapiSession()
+
+    def test_local_session(self):
+        session = self._get_mock_xapisession({})
+        session.is_local_connection = True
+        session.XenAPI = self.mox.CreateMockAnything()
+        session.XenAPI.xapi_local().AndReturn("local_connection")
+
+        self.mox.ReplayAll()
+        self.assertEqual("local_connection",
+                         session._create_session("unix://local"))
+
+    def test_remote_session(self):
+        session = self._get_mock_xapisession({})
+        session.is_local_connection = False
+        session.XenAPI = self.mox.CreateMockAnything()
+        session.XenAPI.Session("url").AndReturn("remote_connection")
+
+        self.mox.ReplayAll()
+        self.assertEqual("remote_connection", session._create_session("url"))
 
     def test_get_product_version_product_brand_does_not_fail(self):
         session = self._get_mock_xapisession({

nova/virt/xenapi/driver.py

@@ -66,6 +66,8 @@ LOG = logging.getLogger(__name__)
 xenapi_opts = [
     cfg.StrOpt('xenapi_connection_url',
                help='URL for connection to XenServer/Xen Cloud Platform. '
+                    'A special value of unix://local can be used to connect '
+                    'to the local unix socket.  '
                     'Required if compute_driver=xenapi.XenAPIDriver'),
     cfg.StrOpt('xenapi_connection_username',
                default='root',
@@ -782,6 +784,9 @@ class XenAPISession(object):
 
     def _create_session(self, url):
         """Stubout point. This can be replaced with a mock session."""
+        self.is_local_connection = url == "unix://local"
+        if self.is_local_connection:
+            return self.XenAPI.xapi_local()
         return self.XenAPI.Session(url)
 
     def _unwrap_plugin_exceptions(self, func, *args, **kwargs):

nova/virt/xenapi/pool.py

@@ -249,7 +249,7 @@ class ResourcePool(object):
             "url": sender_url,
             "user": CONF.xenapi_connection_username,
             "passwd": CONF.xenapi_connection_password,
-            "compute_uuid": vm_utils.get_this_vm_uuid(),
+            "compute_uuid": vm_utils.get_this_vm_uuid(None),
             "xenhost_uuid": self._host_uuid,
         }
 

nova/virt/xenapi/vm_utils.py

@@ -1878,7 +1878,14 @@ def _get_sys_hypervisor_uuid():
         return f.readline().strip()
 
 
-def get_this_vm_uuid():
+def get_this_vm_uuid(session):
+    if session and session.is_local_connection:
+        # UUID is the control domain running on this host
+        host_ref = session.get_xenapi_host()
+        vms = session.call_xenapi("VM.get_all_records_where",
+                                  'field "is_control_domain"="true" and '
+                                  'field "resident_on"="%s"' % host_ref)
+        return vms[vms.keys()[0]]['uuid']
     try:
         return _get_sys_hypervisor_uuid()
     except IOError:
@@ -1893,7 +1900,7 @@ def get_this_vm_uuid():
 
 
 def _get_this_vm_ref(session):
-    return session.call_xenapi("VM.get_by_uuid", get_this_vm_uuid())
+    return session.call_xenapi("VM.get_by_uuid", get_this_vm_uuid(session))
 
 
 def _get_partitions(dev):
@@ -2240,7 +2247,7 @@ def ensure_correct_host(session):
     """Ensure we're connected to the host we're running on. This is the
     required configuration for anything that uses vdi_attached_here.
     """
-    this_vm_uuid = get_this_vm_uuid()
+    this_vm_uuid = get_this_vm_uuid(session)
 
     try:
         session.call_xenapi('VM.get_by_uuid', this_vm_uuid)